--- In
DSN_klr650@yahoogroups.com, "Stuart Mumford"
wrote:
> Leave it there.
> .00005 HP isn't worth the hassle.
>
> It's an un-reversible mod, and it won't make a fart's worth of
difference to
> the performance of your KLR.
> I have the exact same set up you do, right down to the L cutout,
the Laser
> can, and the Big Gun head pipe.
> I have a Keihin 150 main (Dynojet and Keihin use different numbering
> systems, a 150 Dynojet jet is not the same as a Keihin 150), the
adjustable
> Dynojet needle with the clip on the second slot from the top, the
drilled
> out slide, the idle mixture screw at 2 1/2 turns out,and I recently
switched
> to Uni air filters. Not a speed demon, but what power there is is
delivereed
> in a smooth tractable fashion, and my bike runs perfect.
>
> K&Ns will clog and stop your engine in extreme dusty conditions. I
don't
> think anyone would give a crap about filtration properties if their
bike
> chokes out in a sand wash 20 miles from anywhere, that's my primary
concern
> when I'm off road. I would rather have a filter admit a little dust
into my
> engine when it's saturated with dirt than one that will just make
the bike
> unrideable. I know what i'm talking about on this issue, I have had
K&N's
> shit on me (twice) under severe dusty conditions, and seen it
happen to a
> good friend of mine once.
>
> I have a still standing offer of a crisp $50 bill to anyone that
can get a
> KLR to dyno over 39hp with just carb and pipe mods. John Lyon has
the
> official challenge email memorized, I think (Lyon, you out there
man?).
> It's just not going to happen, so spend your money on suspension
and enjoy
> the KLR's motor for what it is.
> Post-doohickeyectomy, it's a reliable, solid, durable, great
machine.
>
>
> Good Luck
> CA Stu
something it
> will never be.
Stu, I gotta disagree with you on at least a couple of issues.
I'll start with the easy one--K&N air filters. I actively raced
enduros from 1974 until 1992. Enduros are one of the most dust
choked events that a dirt bike can be put through in Texas. Cross
country is not far behind. You're constantly working your way back
and forth through groups of riders on tight trails. I raced 4
strokes from about 1979 to 1992 which all had K&N filters--some I had
to even engineer to fit from other bikes when a factory stocker
wasn't available. In the worst and dustiest events, some nearly 100
actual ground miles, I never clogged the filter during the event to a
point where I noticed power drop. In some cases there surely had to
be some loss, but it wasn't really noticeable. I would be riding
with or around other riders that I would occasionally see taking
their foam filter out at a reset or gas stop and literally rinsing
the dirt out with gas and putting the filter back in to finish an
event. Some riders would have a spare foam filter in a plastic bag
to swap out at the gas stop in a dusty event. I never saw a K&N
rider have to do this during an event. During post-race service and
cleanup, I would often look at my K&N and wonder how any air was
getting through, but it was working. Also an inspection of the air
boot and carb throat downstream of the filter revealed no noticeable
dirt particles. You mention some K&Ns that were clogged. I wonder
how long they went between cleanings. Because they will go longer
than a foam filter, I've seen people try to run them until they
clog. If you put them on dirt bikes, no one should expect the kind
of service interval you might get on a street vehicle. Dirt bikes
need their filters cleaned frequently no matter what the filters are
made of. I've got K&Ns on just about every vehicle that I can get
them for, including a 180,000 mile '89 full-size GMC Jimmy 4X4. When
properly installed and serviced, they are amazing.
As to the power increase on the airbox mod, you are correct
about not being able to definitively qualify this without a dyno.
The perspective of low end torque and ease of acceleration are often
performance areas that can be skewed by one's personal experience.
Having had 3 previous KLRs, I guess that is why the airbox mod
results impressed me so much. I worked at a shop for 15 years and
had installed KLR aftermarket pipes, K&Ns, and carb jets, but had
never ridden one with the airbox opened up, including any of mine. I
can also tell by the increased jetting (up to a 158 main) to get the
proper air/fuel mixture that a lot more air, and logically power, are
flowing through this engine. That 158 main jet was attained by plug
checks at various throttle runs, and mileage stayed within the same
45-50 original number. I got 60 mpg with this setup once, but that
was only on 3 gal. of fuel at 55-60 mph with a tailwind--ideal
conditions. The one semi-qualifiable performance issue involves how
strongly and quickly this KLR gets to 100 mph--that's with a
calibrated bicycle computer. No KLR I ever rode attains that speed
this quickly. I now wish I had run over to our local 1/8th mile
strip before and after the mod to get a real number. I'm a little
surprised that so many folks are skeptical that there's not at least
a decent power increase to be had by the total airbox mod when one
looks at the OEM airbox intake hole. This is a 650cc single that
takes a pretty big gulp of air occasionally. You combine the airbox
inlet increase and wire mesh removal, and you get a decent increase
in airflow. Now if you have a good aftermarket pipe, high-flow air
filter, and proper jetting, you can attain a noticeable power
increase. As I've said before, open-class motocross power is not
going to jump out of this motor, but a pleasant non-anemic increase
is available.
It would be great to get real dyno run on a fully modified KLR,
but I guess even then you'd have to qualify mileage/wear, proper
jetting, and exhaust issues. Additionally the power curve as to
where and how quickly power and torque developed would be interesting
and meaningful. Here's one thing that's very positive and absolutely
certain about the airbox mod--it's relatively free.
Thad Carey
A15 (but lookin' like Barbie)